Microphone gaffe from the Ant and Dec of British politics

A gaffe by Nick Clegg looks likely to fuel fears among backbench Coalition MPs about his enduring friendship with David Cameron.

After a question and answer session with members of the public, the Lib Dem leader was recorded yesterday telling the Prime Minister: 'If we keep doing this, we won't find anything to bloody disagree on in the bloody TV debates.'

Mr Cameron laughed, before Mr Clegg realised he had left his lapel microphone on. Gordon Brown suffered a similar fate during the General Election campaign when he was recorded describing angry Labour voter Gillian Duffy as a 'bigot'.

Best of friends: Nick Clegg and David Cameron before the question and answer session in Nottingham

Mr Clegg's mistake after walking off the stage at Boots headquarters in Nottingham overshadowed a visit to the city with Mr Cameron to unveil the first of a new wave of enterprise zones.

It will intensify fears among both Lib Dem and Tory MPs that the pair's close relationship shows they are happier with each other than with their own MPs.

Some fear their partnership could even lead a so-called 'purple plot', with the Coalition continuing beyond this Parliament.